I mixed up a small batch from a recipe I found laying about : 20 grains potassium dichromate dissolved in 30 mL 35% nitric acid. The K2Cr2O7 is from
an ebay source, the acid is AR from Allworld Scientific, the water is distilled water from the grocery store.
I'm trying to figure out how I'm misusing it. I should get a bright to dark red glob with a similar stain on fine, sterling, and coin silver.
I get a red to almost brown drop on all silver samples used, and the stain is white on .999 and sterling, and grey on coin. How should the drop be
removed to inspect the stain?
I found it odd that measurement types are mixed (english with metric). Should I have K2Cr2O7 in the solution?Lambda-Eyde - 13-4-2010 at 14:10
What you have in solution is potassium trichromate in equillibrium with potassium dichromate.
Am I answering your question? Your post seems a little vague, what exactly are you asking for?franklyn - 13-4-2010 at 19:31
Schwerter's solution indications
Brass - Dark Brown
Copper - Brown
Nickel - Blue
Palladium - None
Gold - None
- Silver Pure - Bright Red
- Silver .925 - Dark Red
- Silver .800 - Brown
- Silver .500 - Green
Lead - Yellow
Tin - Yellow
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@ ldanielrosa
" the acid is AR " Aqua Regia is Nitric acid plus Hydrochloric acid
Schwerter's is made only with Nitric acid and Dichromate.
Perhaps Lambda-Eyde can say now why your .999 silver
( if you are certain that's what it is ) turns white.
For the same reason coins will turn grey since they are less pure.
" K2Cr2O7 is from an ebay source "
so what is the assay of what purports to be K2Cr2O7 ?
